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Downhill battery full charge causes engine noise

Posted: Sat Jun 23, 2018 10:46 pm
by niroinca
I drive the 2018 Niro hybrid. When coming downhill over a large distance where I'm only using the brakes, as soon as the battery goes to full charge either the ICE or the electric motor comes on full speed. I can tell from the very loud noise it makes. I don't understand why it does that. My first guess was that it is running the electric motor at full speed to burn off the excess charge. It is quite loud so it could be the ICE, but it makes zero sense to burn fuel in this scenario. My other guess is overcharging takes it over the acceptable voltage and trips some circuits. Why won't they simply disengage the charging circuits instead of letting it charge to 100%? Has anyone else experienced this?

Re: Downhill battery full charge causes engine noise

Posted: Sun Jun 24, 2018 8:36 am
by smileymiley
Don't think the battery should be charging that much. Consesus on here is for the battery to peak around 75%. I'd get it checked out by Kia.

Re: Downhill battery full charge causes engine noise

Posted: Mon Jun 25, 2018 9:18 pm
by djbobbins
I took my Niro to the Alps last summer and experienced the same thing - the drive from the mountain resort down into the valley was about 15km of downhill, mainly switchback roads.

The battery gets to fully changed and then the internal combustion engine kicks in; my assumption is that this is to provide engine braking of some sort. I did the same trip on multiple occasions and didn't notice any ill effects.

Re: Downhill battery full charge causes engine noise

Posted: Tue Jun 26, 2018 7:03 pm
by Topicalcat
That comment about engine breaking makes sense. If the battery will accept charge then the action of using the motor to charge the battery will act to retard the car. However once the battery is charged you no longer have that braking effect and for safety sake need the engine.

I would guess that with the throttle closed the engine when it comes on is using little or no fuel, one of the advantages of fuel injection and a closed throttle. I would be interested to hear further comments on this. When I get my Niro and go to France I will have a 30 mile downhill section coming down from the plateau on the Massiff Central on the A75 autoroute after the Milleau bridge down to the coastal plain. I used to come down in a lower gear in my diesel with no throttle and used to record 99.9 mpg which was as much as the display could cope with. In reality it must have been much better than that.

Re: Downhill battery full charge causes engine noise

Posted: Tue Jul 31, 2018 9:47 am
by h2onorth
Hi all interesting topic which has been raised before by a few. Some contributors also mentioned a "hot smell" from battery area which is not mentioned by current topic. During this downhill scenario has anyone tried sport mode and manually put car in 2nd or 3rd (speed permitting).
If so what data from car was obtained and was engine speed raised or lowered?.
I read recently that the PHEw car displays the revs in certain modes of driving, in which case this would be useful in this scenario.
h2onorth

Re: Downhill battery full charge causes engine noise

Posted: Tue Jul 31, 2018 6:38 pm
by JOL54
Nowhere is there a rev counter on my PHEV.

Re: Downhill battery full charge causes engine noise

Posted: Fri Oct 26, 2018 6:27 pm
by jerrytaff
Owners Manual Pages 4-53, 4-54 and and 4-57 show that for the PHEV, if fitted with instrument cluster type B, then the central LCD window displays a rev counter when in sports mode. So, my question is.... which models are fitted with type B? I've only seen type A.

Does the PHEV even exhibit the same behaviour? The HEV tries to maintain the battery charge within a narrow window, so I can understand it using the ICE to apply non-regenerative engine braking when the battery is at the high end of the window. By contrast,the PHEV window is much wider ( 15% to 100%), so I guess that all you need to do is to ensure that the charge isn't too full (say 50%) before entering the long down-hill section, and you will avoid the inefficiency of having to burn off energy to avoid overcharging .

Re: Downhill battery full charge causes engine noise

Posted: Tue Nov 06, 2018 8:14 pm
by niroal
jerrytaff wrote: Fri Oct 26, 2018 6:27 pm Owners Manual Pages 4-53, 4-54 and and 4-57 show that for the PHEV, if fitted with instrument cluster type B, then the central LCD window displays a rev counter when in sports mode. So, my question is.... which models are fitted with type B? I've only seen type A.

Does the PHEV even exhibit the same behaviour? The HEV tries to maintain the battery charge within a narrow window, so I can understand it using the ICE to apply non-regenerative engine braking when the battery is at the high end of the window. By contrast,the PHEV window is much wider ( 15% to 100%), so I guess that all you need to do is to ensure that the charge isn't too full (say 50%) before entering the long down-hill section, and you will avoid the inefficiency of having to burn off energy to avoid overcharging .
Europe PHEV models have the other display (and LED headlights too). If you live at the top of a hill (thinking more of Switzerland than UK) & have home charging then wasteful regen could be an issue in a PHEV. As the HEV doesn't fully charge the battery in normal driving it actually has more capacity for long regen than a fully charged PHEV.

The bit I find annoying with the type A display on a PHEV is if the car is in HEV mode sport mode is manual only, whereas a HEV can have auto sportmode in (obviously) HEV mode.